WERNER MARCH AND 27 



as the case has hardened, it works its way up by means of its rings 

 of spines and the aster (a name proposed for the terminal whorl of 

 spines), until the pupal head lies just below the surface, being often 

 visible from above. The pupa at first is usually of a pale yellowish 

 or greenish color, but darkens as the imago develops within, the 

 process beginning with the eyes. 



Neave observed that in normally fine weather the imagos of all 

 species almost invariably emerged between noon and 3 p.m. They 

 were more irregular during spells of dull and rainy weather. The 

 process of emergence seems to be similar in individuals of a genera, 

 whether Chrysops, HcBmatopota, or Tabanus. The head of the pupa 

 splits in the median dorsal line and the imago rapidly emerges until 

 only the end of the abdomen, which is at first enormously elongated, 

 remains in the pupa case. The wings at this stage are milky white 

 and the darker markings, if any, are barely visible. The unago 

 usually remains in this position for two or three minutes before 

 completely leaving the pupa case. It is capable of flight very soon 

 after this, but if undisturbed sits for about half an hour on any 

 suitable object near by while the wings dry and assume their normal 

 coloration, and the abdomen its normal shape. During this period 

 several drops of a milky white fluid (the meconium) are passed 

 through the anus. 



Bionomics. 



On the bionomics of the tabanids in the early stages we possess 

 many interesting notes by Neave (1915). From the results of a 

 year's collection of adults in one locality, and from other evidence, 

 it is probable that the majority of tabanids, at least of Nyasaland, 

 have only one brood a year. This is certainly true of nearly all the 

 species of Tabanus and of Dorcalosmus fodiens Aust. It is possible, 

 however, that certain species of Chrysops and Hcematopota may be 

 double-brooded; much doubtless depends on the larval food supply, 

 climate, etc. 



According to Neave, in the case of many species the larva grows 

 very slowly after hatching and often takes six months or more to 

 become full grown. It then, especially in species of Tabanus, goes 

 through a resting period, during which it remains buried in mud or 

 sand, sometimes at a considerable depth. In contrast to the lengthy 



